The United States welcomed the Iraqi forces' victory over ISIS, with Secretary of State saying, "We commend the government of Iraq and the brave Iraqi forces that are displaying tremendous perseverance and courage in this fight."

A White House official said President Barack Obama, who is on vacation in Hawaii, had been briefed on the battle and had saluted the Iraqi forces' "courage and determination."

"We will continue to support our partners fighting against ISIL on the ground until it is defeated," the official said, using another acronym for ISIS.

A U.S.-led military coalition is supporting Iraq's campaign to drive the Islamic State group from the country and carried out 630 air strikes during the Iraqi operation in Ramadi.

General Lloyd Austin, head of Central Command which is overseeing the American role in the campaign, said the fall of Ramadi "clearly demonstrates that the enemy is losing momentum as they steadily cede territory."

"Looking ahead, I expect our partners on the ground in both Iraq and Syria, with coalition assistance, to continue to roll back ISIL gains as we work together to defeat this enemy," he added.

Britain congratulated Iraq as well, with Foreign Secretary Philip Hammond speaking after the national flag was raised over the provincial capital of Anbar once it was liberated.

"This is the latest in a series of significant losses for Daesh. These barbaric terrorists have lost 30 percent of the territory they once held in Iraq," Hammond said in a statement, using the Arabic name for ISIS.

"They have been driven out of cities across the country by Iraqi forces, with support from the UK and the global coalition," he added.

British jets have been striking Islamic State targets in Iraq and Syria.

"The Royal Air Force's close air support operations around Ramadi in recent days have played a key role in the battle," Hammond said.

"We will continue to support the government of Iraq as it re-establishes the security, governance and services the people of Ramadi will need as they return to their city.

"This remains a long fight, but the coalition's strategy is succeeding. We will continue to stand with the Iraqi people until Daesh is defeated."

French President Francois Hollande congratulated Iraqi Prime Minister Haider al-Abadi on his army's liberation of Ramadi, saying it was "a major step" in the conflict.

"(Hollande) congratulated him on the liberation of the town of Ramadi by Iraqi forces, which constitutes the most important victory since the start of the fight against the terrorist organization Daesh," the president's office said in a statement following a phone call between the two leaders.

"It's a major step in the re-establishment of the authority of the state in Iraq," the statement added.